The present invention relates to a solution processing apparatus for supplying a developing solution to the surface of a substrate, for example, a semiconductor wafer or the like which has been coated with a resist and subjected to exposure processing to thereby perform developing processing.
In semiconductor device fabrication, a photoresist is applied to a semiconductor wafer as a substrate to be processed, a mask pattern is transferred to the photoresist by exposure processing, and the photoresist is subjected to developing processing to thereby form a circuit pattern.
In a developing processing step here, the so-called puddle method, in which a developing solution is particularly continuously supplied from a nozzle to the semiconductor wafer and heaped on a face on which a pattern will be formed only for a predetermined period of time for a contact therebetween to thereby develop a latent pattern in the applied resist film, is generally employed.
A puddle method using the so-called linear nozzle in which many solution discharge ports are arranged in a straight line at predetermined intervals is the current mainstream. Developing methods using the above linear nozzles are roughly divided into (1) xe2x80x9ca rotation methodxe2x80x9d of performing solution heaping on the wafer by rotating the wafer 180xc2x0 while the developing solution is being discharged from the linear nozzle, and (2) xe2x80x9ca scan methodxe2x80x9d of performing solution heaping by horizontally moving the linear nozzle in one direction with respect to the wafer without rotating the wafer.
The former rotation method is invented from a recent demand for saving of consumption of a developing solution and that solution heaping is performed in a short time and uniformly. However, by the rotation method, there may be cases where chips in the vicinity of the central portion of the wafer that is the rotational center become defective pieces depending on the type of resist.
More specifically, the solution heaping of the developing solution is performed over the entire wafer by rotating the wafer 180xc2x0 with the nozzle being fixed in the rotation method. By such a method, a fresh developing solution is supplied only to a part close to the central portion of the wafer, and thus it is conceivable that development excessively proceeds only at this part compared with a peripheral part. With micro-machining and higher density in recent circuit pattern, resists have been improved in performance, that is, increased in resolution. Accordingly, problems that have been neglected before are coming up, and, for example, in the case in which a chemically amplified resist (CAR) is used, there is a problem that the aforesaid phenomenon obviously occurs, whereby a desired resolution can not be obtained.
On the other hand, by the scan method, though it takes a slightly long time for solution heaping compared with the aforesaid rotation method, the above problem does not occur, and thus this method is recognized as a promising method in recent years.
In the scan developing method, the aforesaid linear nozzle is used to discharge the developing solution from many discharge ports at the same time with the discharge ports being brought close to the surface of the wafer. Then, the linear nozzle is horizontally moved (scan-moved) in parallel to the surface of the wafer to thereby form a developing solution film on the wafer.
The linear nozzle here is configured such that after the developing solution is stored in a solution storage portion provided therein, pressure is applied to the solution storage portion to thereby discharge the developing solution via the aforesaid many discharge ports. In this case, solutions supplied from the discharge ports in the form of vertically split screen spread out to some extent above the surface of the wafer, and adjacent solutions unite with each other to be supplied onto the wafer in curtain form or film form. Then, the linear nozzle is moved in accordance with the discharge speed of the developing solution, whereby the solution flow in film form can be mounted on the wafer.
The important thing in the developing method as described above is that the developing solution is uniformly discharged from all the discharge ports to form a solution flow in film form with a uniform thickness. Just after the discharge, however, the thickness is prone to become nonuniform. Further, depending especially on the type of resist to be applied to the wafer, it is necessary to reduce the discharge amount and the discharge speed of the developing solution so as to decrease the influence of impact and the like exerted on the resist. In this case, it becomes further difficult to form a solution flow in film form with a uniform thickness.
On the other hand, there is a linear nozzle provided with a discharge port in slit form having a length corresponding to a diameter of the wafer. This nozzle is generally called a slit nozzle, in which unevenness in discharge pressure is prone to occur, and therefore it is further difficult to form a solution flow in film form with a uniform thickness.
Moreover, in the above-described method, the supply nozzle is moved with a tip of the supply nozzle contacting the developing solution supplied on the wafer, and thus if a supply nozzle made of a hydrophobic material is used, the developing solution is rejected by the surface of the nozzle and it becomes difficult to supply the developing solution to the surface of the wafer in a uniform state, bringing about a problem that development unevenness is likely to occur.
In the case in which a supply nozzle made of a hydrophilic material is used, the developing solution is brought into a state of being pushed out when the supply nozzle is moved at a low scan speed, for example, at about 50 mm/sec, with the result that the developing solution flows to a position ahead of the nozzle in respect to a direction of movement of the nozzle. If the developing solution flows ahead of the supply nozzle as described above, development proceeds at this part, and thereafter the supply nozzle moves to this part and the developing solution is supplied thereto, which is the same as a state in which development is performed twice for this part, development proceeding too much compared with other parts, resulting in nonuniform line width.
If a phenomenon of the developing solution flowing ahead occurs over the entire wafer W and every part is brought to a state of being subjected to development twice here, occurrence of development unevenness can be prevented. However, the developing solution actually flows ahead at some parts and not at other parts, resulting in occurrence of development unevenness and nonuniform line width.
An object of the present invention is to provide a solution processing apparatus capable of discharging a developing solution uniformly from all discharge ports even when, for example, discharge pressure for the developing solution to be supplied is low in development of a scan method using a linear nozzle or a slit nozzle.
Another object of the present invention is to provide a solution processing apparatus capable of performing uniform solution processing on the surface of a substrate.
To attain the above objects, with a primary aspect of the present invention, provided is a developing processing apparatus for supplying a developing solution to a substrate to be processed on which a photoresist film has been formed to thereby perform developing processing, including: a substrate holding mechanism for horizontally holding the substrate to be processed; a developing solution supply nozzle held above the substrate holding mechanism for supplying the developing solution onto the substrate to be processed while moving in a predetermined horizontal direction; and discharge resistance imparting means, disposed behind the substrate in a direction of movement of the developing solution supply nozzle, for imparting discharge resistance to the developing solution discharged from the nozzle.
With the above configuration, the discharge resistance is imparted to the developing solution discharged from the developing solution supply nozzle, thereby making it possible to adjust the discharge state of the developing solution uniform over the entire width of the nozzle. Further, the discharge resistance is imparted to the developing solution, whereby the developing solution just after discharged spreads out, facilitating the formation of a developing solution flow in film form.
According to one embodiment, the discharge resistance imparting means is provided at a developing solution discharge start position of the developing solution supply nozzle. This configuration makes it possible to increase the discharge pressure just after the start of discharge to thereby make the discharge state uniform.
Further, according to another embodiment, the developing solution supply nozzle has a developing solution discharge port provided over a region corresponding to a width of the substrate to be processed. In this case, the developing solution discharge port of the developing solution supply nozzle may be composed of a plurality of discharge ports provided side by side over the region corresponding to the width of the substrate to be processed or a discharge port in slit form provided over the region corresponding to the width of the substrate to be processed.
According to one embodiment, the discharge resistance imparting means is a plate member or a rod member provided close to an under face of the developing solution supply nozzle and having a width slightly greater than a width of the discharge ports (port)of the developing solution supply nozzle.
According to still another embodiment, the discharge resistance imparting means is a plate member provided close to an under face of the developing solution supply nozzle and having a drain passage capable of draining the developing solution.
Further, according to another embodiment, the discharge resistance imparting means is gas-flow blasting means provided to face an under face of the developing solution supply nozzle for blasting gas-flow to the discharged developing solution.
A solution processing apparatus according to the present invention is characterized by including a substrate holding portion for nearly horizontally holding a substrate; and a supply nozzle with discharge ports formed over a length nearly equal to or greater than a width of an effective area of the substrate, provided to be movable relative to the substrate, for supplying a processing solution to the surface of the substrate held by the substrate holding portion, the supply nozzle being configured to move relative to the substrate with allowing a tip of a member forming the discharge ports to contact the processing solution supplied on the surface of the substrate to supply the processing solution to the surface of the substrate, and the member forming the discharge ports being hydrophobic at a forward part in respect to a direction of movement of the supply nozzle and contacting the processing solution on the surface of the substrate.
In this configuration, even if the processing solution on the surface of the substrate is likely to flow to a position ahead of the supply nozzle in respect to the direction of :movement during the supply of the processing solution from the supply nozzle to the surface of the substrate, upon touching the forward part of the member forming the discharge ports, the processing solution is rejected by the hydrophobic surface of the member, so that occurrence of the phenomenon of developing solution flowing ahead can be prevented.
Further, in the present invention, the member forming the discharge ports of the supply nozzle may be hydrophilic at a part behind the hydrophobic part in respect to the direction of movement of the supply nozzle and contacting the processing solution on the surface of the substrate, and in this case, an adhesion strength of the processing solution to the part is large, thus further preventing the processing solution from flowing ahead.
xe2x80x9cHydrophobicxe2x80x9d means here that surface tension of the hydrophobic part is smaller than the original surface tension of the material of the member forming the discharge ports of the supply nozzle, and xe2x80x9chydrophilicxe2x80x9d means that surface tension of the hydrophilic part is larger than the original surface tension of the material of the member forming the discharge ports of the supply nozzle.
Furthermore, the present invention is characterized by including a substrate holding portion for nearly horizontally holding a substrate; and a supply nozzle with discharge ports formed over a length nearly equal to or greater than a width of an effective area of the substrate, provided to be movable relative to the substrate, for supplying a solution to the surface of the substrate held by the substrate holding portion, the supply nozzle being provided with a guide for guiding the processing solution discharged from the discharge ports to the surface of the substrate, on the front side in respect to a direction of movement of the supply nozzle in a manner to adjoin to a member forming the discharge ports. Moreover, a tip of the guide may be curved to locate behind the discharge ports in respect to the direction of movement of the supply nozzle.
In this configuration, even if the processing solution on the surface of the substrate is likely to flow to a position ahead of the supply nozzle in respect to the direction of movement during the supply of the processing solution to the surface of the substrate by the supply nozzle, the processing solution is prevented from flowing to the position ahead of the guide by the guide, so that occurrence of the phenomenon of developing solution flowing ahead can be prevented.
These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.